The word “trust” in the school of St. Faustina’s spirituality describes the relation of man towards God, while the word “mercy” characterises interpersonal relations whose origin, model and motive lies in the merciful love of God. Jesus said to St. Faustina, I demand from you deeds of mercy, which are to arise out of love for Me. You are to show mercy to your neighbours always and everywhere. You must not shrink from this or try to excuse or absolve yourself from it. I am giving you three ways of excersing mercy toward your neighbour: the first – by deed, the second – by word, the third – by prayer. In these three degrees is contained the fullness of mercy, and it is an unquestionable proof of love for me. By this means a soul glorifies and pays reverence to My mercy (Diary 742).

Nowadays there exists plenty of false conceptions of mercy, which are often identified with indulgence, pity, the denial of justice, therefore the proper and profound conception of mercy, which Sister Faustina had, deserves attention. Human mercy for St. Faustina is very strictly related with God’s mercy and so it is based on objective truth – the word of God; it sets up the fulfillment of the demands of justice, which is the basic limit of love and it fruits in concrete deeds. Mercy is the flower of love (Diary 651) or deed’s mercy (cf. Diary 651), Sister Faustina would write. In her life and in the writings witnessing of mercy towards neigbours must include first of all a dignity of needy man, and next his corporal and spiritual needs. A dignity of every man, given him through God already on the reason of creation and redemption, is this value, which is common for needy one and for person doing good. Noticing this dignity, given through God, in needy man and underlined by Christ, had an essential meaning for practise of mercy, and marks out the personalistic school of St. Faustina’s mercy from other models which appeared in the history of the Church.

In this interpretation, mercy – which has its source, model and motive in God, and which concetrates on man’s dignity – in Sister Faustina’s school of thought determines a style of life. Not only does it encompass sporadic or occasional acts of mercy performed towards those who are in need, but it also requires a Christian attitude towards the neighbour in all his dimensions, guided completely by merciful love. I want to be completely transformed into Your mercy, Sister Faustina prayed, and to be Your living reflection, O Lord. May the greatest of all divine attributes, that of Your unfathomable mercy, pass through my heart and soul to my neighbour (Diary 163). This transformation of life into mercy denotes exactly an entire life-style, and not only one of its numerous features.

Coming to know the merciful love of God, penetrating it ever more deeply, as well as experiencing it led Sister Faustina to the attitude of childlike trust toward God. Furthermore, it awakened the ardent desire to reflect this attribute of God in her own heart and deeds. Each of Your saints, she prayed, reflects one of Your virtues; I desire to reflect Your compassionate heart, full of mercy; I want to glorify it. Let Your mercy, O Jesus, be impressed upon my heart and soul like a seal, and this will be my badge in this and the future life (Diary 1242).

In theological dictionaries and handbooks, love has its own definition. So does the virtue of mercy. Based on St. Thomas’ teaching, Catholic theology defines love as the virtue that wishes good to someone, whereas mercy as the virtue that seeks to remove an evil that distresses him. Mercy, writes St. Thomas, is heartfelt sympathy for another’s distress, impelling us to succor him if we can. So love differs from mercy only in its object; love aims at increasing good, and mercy at remedying evil. In traditional theology, mercy is, then, one of the moral virtues. But of all the virtues which relate to our neighbour, writes St. Thomas, mercy is the greatest, even as its act surpasses all others, since it belongs to one who is higher and better to supply the defect of another, in so far as the latter is deficient.

In his encyclical Dives in Misericordia, the Holy Father John Paul II sheds new light on the very concept of mercy. In his view, mercy is not only a virtue, but an attitude entailing a whole set of moral perfections, among which creative love ranks first since it does not allow itself to be conquered by evil, but overcomes evil with good.

It is precisely this understanding of mercy that applies to the spirituality of Sister Faustina as well. Thus, it denotes not a single virtue but an all–encompassing attitude toward our neighbour, made up of a number of moral perfections. Sister Faustina described mercy very simply, saying that love is the flower, mercy the fruit (Diary 949).

Mercy, for Sister Faustina, is an attitude that embraces every type of conduct toward neighbour, and it should penetrate and characterize our every contact with others, every deed, thought, and word. So, with the help of grace, she wanted to be completely transformed into mercy (Diary 163); and she prayed that her eyes, ears, tongue, hands, feet, and above all that her heart be merciful (Diary 163).

In the school of Sister Faustina, mercy denotes an all–embracing attitude toward neighbour in which the supernatural virtue of love plays a fundamental and creative role. For charity does not love God only in man, but man in God, and man himself for God. This is also why we can ascribe to the attitude of mercy those attributes that St. Paul uses in defining love. Paraphrasing his hymn about love, taken from the First Letter to the Corinthians, we can say: mercy is patient, kind, not jealous, not pompous, not inflated…etc. (1 Cor 13:1–7).

An ardent love of God, wrote Sister Faustina in the Diary, sees all around itself constant opportunities to share itself through deed, word and prayer (Diary 1313). This incessant sharing of itself in Sister Faustina’s life touched, above all, the spiritual needs of man – especially of those people who had lost their way in life, who could no longer see the meaning of their life, who had gone astray on the path of salvation. It was precisely this love of souls that led Sister Faustina even to offer her life in sacrifice. Since she had a profound understanding of the value of the human soul, which is immortal, she hastened to help particularly those who were at risk of losing their salvation.

The close connection that exists between the mystery of Divine Mercy and human mercy deserves special attention and emphasis. In Sister Faustina’s view, the attitude of mercy toward neighbour has its source in the mystery of Divine Mercy, springing and flowing from it. Likewise, she finds its reason in it, in the sense of being its model and its cause.

Sister Faustina’s model for practising mercy was the Lord Jesus himself – Mercy Incarnate. I am learning how to be good from Jesus, she wrote in the Diary, so that I may be called a daughter of the heavenly Father (Diary 669). The contemporaries of Jesus said that He spent His life on earth doing good to everyone. This example of Jesus and, in particular, His bending mercifully over every person suffering in soul, over every sinner – even leading up to His sacrifice on the cross – was for her the sole model. In difficult moments, when she did not know how to act toward her neighbour, she would ask: What would Jesus do in my place? The account of a certain encounter Sister Faustina had with a lay person who had abused her goodness perfectly illustrates how she imitated Jesus’ example, At the first moment I saw her, she wrote in her Diary, the blood froze in my veins, because there stood before my eyes all that I had to suffer because of her. …And the thought came to me to tell her the truth, firmly and immediately. But at the same moment, the mercy of God came before my eyes, and I resolved to act toward her as Jesus would have acted in my place. I started to talk to her gently, and when she expressed the wish to talk to me alone, I then, in a very delicate manner, made known to her clearly the sad condition of her soul. I saw that she was deeply moved (Diary 1694).

For Sister Faustina, the Divine Mercy is the foundation of the attitude of mercy toward neighbour, not only in the sense of model but also in the sense of cause. It ought to be – in her opinion – a certain sharing in the mercy of God. Sister Faustina was well aware that by doing good deeds out of love for Christ, she was taking part in dispensing God’s mercy to the world, since God makes use of people to show His goodness. Hence, she desired to be completely transformed into mercy and to be a living reflection of the Divine Mercy so that the greatest of all divine attributes, that of His unfathomable mercy could pass through her heart and soul to her neighbour (Diary 163). The Lord Jesus himself spoke to her about this dependence between human and Divine mercy. My daughter, He taught her in a conference on mercy, know that My Heart is mercy itself. …I desire that your heart be an abiding place of My mercy. I desire that this mercy flow out upon the whole world through your heart. Let no one who approaches you go away without that trust in My mercy which I so ardently desire for souls (Diary 1777).

Mercy shown toward other people must be carried out in the spirit of Christ if it is to be a participation in God’s mercy. This is why the Lord Jesus told Sister Faustina that her heart ought to be an abiding place of His mercy so that His mercy could flow out upon the whole world through her heart. Therefore, this is neither a question of some natural charity nor of some motive of philanthropy; rather, it is a matter of mercy shown to others out of love for Jesus and in His spirit. This requires that we see the other person with the eyes of faith as a being created in the image and likeness of God (Gn 1:26) and redeemed not with perishable things like silver and gold, but with the precious blood of Christ (1 Pt 1:18), as a child of God destined to inherit the goods of the heavenly kingdom, destined to share in the life of the Triune God. Sister Faustina practised this way of looking at and approaching her neighbour. The more difficult she found it to deal with a person, the more she strove to see in this person Christ calling her to assume the attitude of mercy.

Furthermore, Sister Faustina perceived the interdependence of the attitude of trust toward God and the attitude of mercy toward neighbour. She ascertained that the more complete the trust in God is, the more sacrificial and effective is the help given to neighbour. One word from a soul united to God, she wrote in the Diary, effects more good in souls than eloquent discussions and sermons from an imperfect soul (Diary 1595). She knew very well that in order to show mercy in the spirit of Christ, one must live in union with Him. In order to recognise and serve Him in others, one must first learn to live with Him in one’s soul (Diary 503). She also noted the reverse relationship when writing, I have learned and experienced that souls living in love are distinguished in this: that they are greatly enlightened concerning the things of God (Diary 1191), which consequently leads to an attitude of deeper trust.

What we have said so far about trust and mercy in the school of Sister Faustina’s spirituality already allows us to see that we are dealing with the very foundations of Christian life. Through the attitude of childlike trust in God and mercy toward neighbour even to the sacrifice of her life, Sister Faustina fulfilled perfectly in her life the greatest commandment of love of God and neighbour, and thereby the very essence of Christianity.